Alnar: Hi,
I do not think the language is the problem, I suppose it has more to do with Windows 10 itself.
I installed the game and the Collection Upgrade on my old Windows 7 laptop, which is in French too (I install my games in English though, as I don't like French translations) and there, the game starts without problem.
So, it is a rather strange problem, as vanilla game works just fine on my windows 10, but won't start with DLC's installed. I don't know if turning the whole OS in English would solve the problem, but could try if GOG Support doesn't come with a solution.
In the worst of cases, I can play on my old laptop, but well, it's 6 years old and has become rather slow.
Hi Alnar,
If it is running on 7.....(and even a french version ;) )
The usual suspects ;)
directplay?
directx9.0c?
Those two are the most common ones causing troubles. From some other games I know that either the games or Win is having troubles if there is no CD/DVD being installed, can be worked around by installing virtual clone drive or using the build in Win10 iso mount manager (or however they called it).
All I can think of in the moment......(afterthought.....permission rights while installing the DLC?....)
For Installing in English the games, yup those translations......